Great choice! It really depends upon the driving experience that you both want.

The Giulietta/Giulias can feel quite old these days compared to moderns, even though they were very advanced for their time. You can get them in 1300 or 1600, but neither engine is a snorter by modern standards. Also the hood is not as easy to operate as the later cars. Cruising around Italy in one, though - wow, what joy! They are utterly drop-dead gorgeous and glacially cool!

The 1600 Duetto is a star too, but the boot of these boat-tails is shallower than the later Kamm-tail cars. How much luggage you got?

The Kamm-tail cars (Series 2) are the best looking of the later cars, IMHO, and the best engine is the 1750 - it really sings. The 2000 has a more modern feel because it lugs willingly from low revs - helpful in traffic.

The Series 3 cars are the ugly ducklings of the set, although their dynamics are not much different from the S2s. One of these would be OK if you can't get anything else - it's still an Alfa Romeo Spider!

Series 4s were an attempt by Alfa to make a 20-year old car act a bit more modern, with fuel injection and a plush cabin, which stunts performance. IMHO it doesn't work, because the beauty of the cars is in their simplicity and sheer driveability.

Then there are the 916 wedges from the nineties. They're becoming quite cool these days, especially the ones with the V6 engines - a noise to die for! But maybe not quite a classic yet?

Finally, there are the "Brera" Spiders which, although very beautiful, are modern cruisers, and therefore don't really count. Yet.